INTRODUCTION OF NONINDIGENOUS SPECIES
Global shipping moves 80 percent of the world's commodities and is fundamental to world trade. Humans and ships have moved across the oceans for centuries; however trade routes and the vessels that sail them have changed and continue to change, as do port, estuarine, and ocean environments. This dynamic environment favors continued introductions of nonindigenous organisms—including mice, rats, cockroaches, water fleas, jellyfish, crabs, clams, fish, and snails—transported to new locations by ships. The potentially adverse effects of such introductions were illustrated by the discovery in the 1980s of the fouling European zebra mussel in the Great Lakes, a toxic Japanese dinoflagellate in Australia, and a carnivorous North American comb jellyfish in the Black Sea. These three introductions alone have cost many millions of dollars in remedial action; have had deep and broad ecological repercussions; and have focused government, public, and scientific attention on the role of shipping as a dispersal vector for nonindigenous aquatic organisms. Action to control unwanted introductions is being considered by individual nations and in the international arena under the auspices of the International Maritime Organization (IMO). In 1990, the U.S. Congress enacted P.L. 101-646 (the Nonindigenous Aquatic Nuisance Prevention and Control Act aimed at preventing future introductions of potentially harmful aquatic nonindigenous species and controlling existing unintentional introductions. The objective of developing strategies for managing ballast water is to reduce the likelihood of new introductions to an acceptable level without compromising ship safety.
Oceangoing ships disperse aquatic organisms through the uptake, transport,
and subsequent discharge of water from ballast tanks. It has been estimated that more than 3,000 species of animals and plants are transported daily around the world in ballast water, which is required for safe operation under a range of conditions.1 For the purposes of this study, the term ballast includes sediment, which is the debris suspended in ballast water as it is loaded that subsequently accumulates on horizontal surfaces in ballast tanks. Ship owners since time immemorial have endeavored to avoid using ballast, preferring to carry revenue-earning cargo. Nevertheless, ballast is always necessary for the successful and safe operation of ships.
Any approach to managing ballast water and controlling introductions of nonindigenous aquatic species must take into account that there may be several source regions and release sites of ballast water on any sea voyage. The biota in ballast water are correspondingly diverse, and predicting the presence of a particular unwanted species in a particular vessel or certifying a particular vessel as free of or safe from all unwanted species is extremely difficult. The diversity of potential introductions and the numerous environmental factors (e.g., water temperature, nutrient levels, and the extent and nature of pollution) determining the fate of organisms discharged with ballast water make it impossible to predict what the next introduction will be or when and where it will occur. Nevertheless, it can be stated with confidence that further introductions will take place and that ballast water is an important vector contributing to the dispersal of nonindigenous aquatic organisms.
POTENTIAL CONTROL STRATEGIES
Changing ballast at sea is currently the favored technique for reducing the risk of introducing nonindigenous aquatic organisms into the marine environment through discharged ballast water. Ballast water loaded in port or taken on board while transiting inshore waters is charged with ocean water during passage between ports of call. This method is usually effective because most freshwater estuarine, and inshore coastal organisms cannot survive when discharged into the ocean environment. Similarly, freshwater, estuarine, or inshore coastal waters are inhospitable to oceanic organisms. One of the main functions of ballast is to ensure the stability and manageability to ships at sea. Therefore, altering the ballast condition while under way may jeopardize vessel safety. In addition, the design of most ballast systems does not permit the removal of all ballast and associated biota. Thus, while changing ballast may be an acceptable and effective control method under certain circumstances, it is neither universally applicable nor totally effective, and alternative strategies are needed.
The committee categorized the range of potential strategies for controlling ballast water as follows:
On or before departure. Control is based on preventing or minimizing the intake of organisms when ballast water is loaded at the port of origin.
En route. Control is based on the removal of viable organisms by shipboard treatment or ballast change prior to the discharge of ballast water at the destination port.
On arrival. Control depends on preventing the discharge of unwanted organisms that could potentially survive in the new environment.
The viability of different control options depends not only upon their biological effectiveness but also on vessel size and type and the loading and discharge capacities of ballast pumping and piping systems. Given this diversity of vessels and the complexity of ballasting patterns, the committee determined that flexibility in managing ballast water is essential for adequate protection against introductions of unwanted nonindigenous aquatic organisms.
Biological scientists cannot currently state what level of ballast water control is effective, and existing guidelines for controlling introductions of nonindigenous aquatic nuisance species do not identify an acceptable level of risk. Risk-based approaches to managing ballast water, using quantitative risk assessment methodology, are being investigated in the United States and Australia.
There is currently no universally applicable option for controlling ballast water that can totally prevent the unintentional introduction of nonindigenous aquatic nuisance species. The use of available control methods is limited by requirements for safety, environmental acceptability, technical feasibility, practicability, and cost effectiveness. Nonetheless, there are a number of control options that could be undertaken today that would immediately reduce the transport of nonindigenous species by ballast water. These options include avoiding ballasting if water is likely to contain unwanted organisms (for example, in areas of sewage discharge or high sediment loads). A plan for managing ballast water developed in conjunction with the ship cargo plan would provide flexibility for meeting contingencies and avoiding ballasting in certain locations.
Both shipboard and shore-based facilities for treating ballast water merit further investigation. The concept of shore-based reception facilities for oily ballast has gained acceptance, although such facilities are not widely used. Shore-based treatment of ballast water may have some advantages, but there is no precedent in the United States for recovering associated infrastructure costs, and shipboard treatment is more likely to be implemented.
In the absence of a universally applicable method of managing ballast water, the committee identified a need for additional research and development to improve methods of killing or removing organisms in ballast water. In the view of the committee, international coordination of research on ballast water would both stimulate activity and avoid duplication of effort.
SHIPBOARD TREATMENT OPTIONS
Shipboard treatment provides the most flexibility in managing ballast water. The committee identified 10 major categories of candidate shipboard treatment technologies: biocides (oxidizing and nonoxidizing), filtration, thermal treatment, electric pulse/pulse plasma treatment,2 ultraviolet, acoustics, magnetic, deoxygenation, biological, an anti-fouling coatings. A number of these technologies are used extensively in waste-water treatment. However, the requirements for the shipboard treatment of ballast water are somewhat different. The space and power available on board ship are limited, and very large volumes of ballast water must be treated without compromising the safety of the ship or crew.
As a basis for gathering information on candidate systems, the committee developed a questionnaire about the options for treating ballast water. Two representative scenarios of ballasting requiring treatment were defined:
System A. Flow rate of 2,000 m3/h and tank volumes of up to 25,000 m3, with residence times as short as 24 hours.
System B. Flow rate of 20,000 m3/h and tank volumes of up to 25,000 m3, with residence times as short as 24 hours.
Data were sought on a range of system characteristics, including equipment and space requirements; capital and operating costs; safety; effectiveness in destroying or removing a range of aquatic organisms; byproducts of treatment; operation, training, and manpower requirements; and performance over a range of temperatures and salinities in the presence of sediment. Responses to the questionnaire were received from equipment suppliers, technology developers, and research organizations. Additional information on candidate treatment technologies was obtained from product literature and articles in scientific and technical journals.
The committee identified a series of parameters for rating technologies for potential application in shipboard treatment of ballast water. Safety is critical in evaluating strategies for managing ballast water. In addition, strategies are only worthwhile if they effectively reduce the number of viable organisms in ballast water. Therefore, safety and effectiveness were used as the first gate in evaluating candidate systems. Four technologies were judged by the committee to meet requirements for safety and effectiveness: biocides, filtration (media and film), thermal, and electric pulse/pulse plasma. Biological treatment and antifouling coatings were not evaluated in any detail. The other candidate systems were deemed safe but did not meet the criterion for effectiveness in treating the wide range of organisms found in ballast water.
The committee evaluated the technologies that met the safety and effectiveness criteria in terms of other important criteria for shipboard use, namely:
commercial availability of proven systems, including marine systems
production of chemical residuals during treatment
possibility of increasing effectiveness by recirculating ballast water
cost, both capital and operating (including possible impact on crew size)
size and complexity
ease of maintenance
ease of monitoring performance
Although no single technology received good ratings in all categories, the committee identified several promising candidates. The most promising technologies for the successful shipboard treatment of ballast water are physical separation methods, particularly constant backwash fine screening. Adding low concentrations of biocides to kill unwanted organisms is also a promising option. Thermal treatment may be practical for certain vessels on specific trade routes. Other technologies require significant development before they can be considered suitable for shipboard treatment of ballast water. The absence of an off-the-shelf treatment technology suitable for use on board ship further highlights the need to consider diverse approaches to managing ballast water.
Monitoring ballast water has two major purposes in the context of current efforts to control introductions of nonindigenous aquatic nuisance species. First, monitoring (supported by appropriate record keeping) is needed to audit methods of controlling ballast water for compliance with regulations or guidelines; therefore, monitoring is an integral part of the process for managing ballast water. Second, monitoring is a research and development tool for assessing the effectiveness of ballast water treatments, increasing understanding of the nonindigenous species problem, and developing plans for managing ballast water. Thus, the committee identified monitoring as a very important component of both current and future efforts to control introductions by ships' ballast water.
Shipboard monitoring systems need to be safe, inexpensive, rugged, compact, easy to use, and quick to operate—even for personnel with little training. Onboard monitoring imposes more constraints and requirements than land-based monitoring. Because implementing measures for managing ballast water will require practical measures for verification, accountability, and responsibility, automated monitoring methods are desirable.
The monitoring needed in any given situation will be closely linked to approaches adopted for managing ballast water. In general, the monitoring effort and associated costs will decrease as the effectiveness and cost of strategies for
managing ballast water increase. The trade-off between levels of treatment and monitoring must be taken into account in assessing the cost effectiveness of strategies for managing ballast water.
The committee identified three levels of monitoring that might be needed for vessels that have either changed ballast at sea or have taken no action to control potential nuisance organisms in ballast. Vessels that have undertaken shipboard treatment of ballast water represent a somewhat different situation because monitoring requirements will generally be determined by the treatment method. The three proposed levels are as follows:
Level I. Log of change events and basic water quality parameter description
Level II. Basic bioactivity and indicator species description
Level III. Advanced biological analysis
Level I monitoring is the simplest and least expensive; level III is the most complex and expensive and is not likely to be practicable with existing technology. The committee anticipates that monitoring will be conducted at the lowest level necessary for determining with confidence that the discharge of ballast water does not pose an unacceptable risk of introducing nonindigenous aquatic species.
The committee believes that level I monitoring could be readily implemented and that it would be effective for ships that change ballast at sea. The basic parameters indicative of water quality—turbidity, salinity, temperature, dissolved oxygen content, and pH—can be readily measured using commercial instruments and test kits suitable for marine applications. In addition, records of ballast water operations are already kept by the vast majority of vessels. Examination of these records, in conjunction with testing of basic water quality parameters to confirm ballast movements, would generally provide adequate assurance that the ballast tanks contain oceanic rather than estuarine water. Thus, mandatory maintenance of ships' logs and records with data on all ballast-water movements for verification by shore officials would assist in implementing control measures and would reduce the need for detailed monitoring in many instances.
Vessels that have not treated or changed ballast water at sea are unlikely to be able to rely on level I monitoring approaches and will require level II or level III analyses.3 The presence of life in ballast water (level II monitoring) can easily be determined in a laboratory environment by assessing levels of bioactivity based on measurements of photosynthetic pigment, adenosine triphosphate, nucleic acids, and nutrients. Advanced biological analysis (level III monitoring) requires the taxonomic identification of organisms, possibly to species level; is time consuming and expensive; and cannot currently be performed on board ship. It may be possible to develop inexpensive biomonitoring techniques for ballast water that are amenable to shipboard use.
Monitoring ships' ballast is complicated by the need to analyze not only the water column but also the sediment that accumulates at the bottom of tanks and holds. Periodic monitoring of sediment is necessary because sediment may be a source of transported organisms.
Under certain circumstances onboard monitoring systems are not practical or are too expensive to install. A system of ballast water sampling and dispatch has been suggested as an alternative to shipboard monitoring. Developing this approach for a range of organisms represents a major challenge in terms of both sampling and testing. It is also not clear if potentially harmful species can be identified as such prior to their introduction. However, baseline sampling of ports for the presence of specific organisms to standardized, internationally accepted criteria would be helpful in determining the risk associated with voyages between specified ports. Port baseline surveys represent a significant scientific undertaking and would require periodic updating.
REGULATIONS AND GUIDELINES
The U.S. Coast Guard regulations for controlling nonindigenous species in ballast water in the Great Lakes, which were promulgated in response to P.L. 101-646, are the only mandatory regulations for managing ballast water in effect in the United States. The regulations apply to vessels that have operated outside the exclusive economic zone of either the United States or Canada. Overseas, Chile and the port of Haifa in Israel have introduced requirements making it mandatory that ballast water be changed prior to being discharged.
In addition to these mandatory requirements, there are a number of international, national, regional, state, and local initiatives to control introductions of nonindigenous aquatic nuisance species. In particular, the IMO has developed guidelines for preventing the introduction of unwanted aquatic organisms from discharged ballast water and sediment, and IMO member states have been requested to apply these guidelines on a voluntary basis. The Marine Environment Protection Committee of IMO is currently drafting a set of regulations for a possible new annex to MARPOL 73/784 that would make use of the guidelines mandatory. If acceptable to IMO's contracting nations, the new annex could be ratified around the turn of the century. The guidelines can be continuously updated, incorporating the results of research and development and improved technologies, without changing the regulations of the annex.
In an international context, the committee concluded that regulations to control introductions would be most effective in the form of an amendment to an existing international convention or treaty. The introduction of unilateral legislation and regulations by individual nations would result in a complicated ''patchwork" of
national requirements, which operators of vessels in international trade would find difficult to understand and comply with. The committee proposes that, in the interest of simplifying compliance, the United States develop domestic guidelines for managing ballast water that mirror the IMO voluntary guidelines. The implementation of national guidelines would be facilitated by a targeted education program for those directly involved in managing ballast water.
Regional initiatives include those in the Great Lakes and Chesapeake Bay. A notable feature of these regional initiatives is the involvement of a broad group of participants, including the representatives of the shipping industry, ports, the scientific community, and regional, state, and federal governments. Cooperation at the regional level goes beyond legal mandates. The committee judged this kind of cooperation to be an important factor in addressing the problem of nonindigenous species transfer, which is not simply an issue for the shipping industry but has implications for society as a whole.
The committee identified measures that could be taken now—in parallel with research and development and demonstration programs—to facilitate managing ballast water. The mandatory maintenance of logs recording all ballast water movements was addressed above. The committee also anticipates that onboard monitoring of basic water quality parameters could be implemented in the near future. In addition, the committee determined that the development of a plan to manage ballast water, in conjunction with the cargo plan, would provide flexibility in loading and discharging ballast water. The plan should be mandatory when the ports of call include one or more known sources of unwanted organisms.
On the basis of its review, the committee recommends the following:
Recommendation for the U.S. Coast Guard. Managing the unintentional introduction of nonindigenous organisms into U.S. waters through ballast water should follow two parallel courses:
Support current international activities conducted under the auspices of IMO.
Introduce national voluntary guidelines to minimize the risk of introductions until such time as mandatory international standards can be developed. These guidelines should require a plan for ballast water loading and discharge, developed in conjunction with the cargo plan for each voyage.
Recommendation for the Aquatic Nuisance Species Task Force. The following actions should be taken as part of the cooperative national program to prevent unintentional introductions of nonindigenous organisms through ballast water:
The United States should support and encourage the early elaboration of a new annex to MARPOL 73/78 making the existing voluntary guidelines mandatory; meanwhile, the IMO-sponsored voluntary guidelines should be continuously reviewed and updated.
The cognizant U.S. authority,5 as a matter of priority, should be tasked with developing domestic guidelines to minimize the translocation of unwanted nonindigenous organisms among U.S. ports by vessels engaged in trade along U.S. coasts. All interested parties should be involved from an early stage in formulating guidelines and in developing ways to implement them.
The associated U.S. authorities should sponsor and encourage further research and development for killing or removing aquatic organisms in ballast water. In this regard, options for treating ballast water should not be limited to technologies for shipboard use. Shoreside treatment should be investigated as a possible alternative.
Recommendation for the Aquatic Nuisance Species Task Force. National research and development, including one or more demonstration projects, should focus on the following:
optimizing the filtration approach to treating ballast water
identifying the level of biological activity that indicates that treatment has reduced the risk of species introduction to an acceptable level
developing automated monitoring systems suitable for shipboard use
To avoid duplication of effort, these activities should take into account related research and development in other countries.
Recommendation to the Aquatic Nuisance Species Task Force. The results of this study should be disseminated to coastal states, including states bordering the Great Lakes.
Recommendation for the U.S. maritime industry. At the same time research and development are undertaken to address long-term solutions for controlling introductions of nonindigenous aquatic organisms, the U.S. maritime industry should pursue implementation of a combination of practices for managing ballast water and the control options described herein, within the framework of existing international guidelines.
Recommendation for the member states of IMO. Future international considerations should include establishing guidelines for baseline sampling of ports for specific organisms. Samples should be tested to agreed-upon international standards to facilitate comparisons of the water of each ballast uptake port with the water of receiving ports.
Recommendation for the member states of IMO. In future discussions and updates of the existing voluntary guidelines (IMO Assembly Resolution A.774(18), 1993), consideration should be given to the maintenance of appropriate logs and records of ballast water movements and any management practices used. These data could be valuable when used in conjunction with basic water-quality measurements to verify that ballast water has been effectively managed.